Aspen Physical Property System - Physical Property Models

At the pure fused salt state:
The symmetric reference state defined by Eq. 3 is restricted to systems
containing a single electrolyte component. For multi-electrolyte systems, the
symmetric reference state can be generalized from Eq. 3 as follows:
120 2 Thermodynamic Property Models
(6)
(7)
(8)
(9)
(10)
where I applies to all molecular components in the system. The symmetric
reference state is a molecular-component-free media.
Infinite-dilution aqueous solution
The condition of infinite-dilution solution for ionic components can be written
as follows:
(11)
This condition applies to all ionic components in the solution. In infinitedilution
aqueous solutions, water must be present and is assumed to
represent the entire solution, so the unsymmetric reference state can be
written as follows:
This equation applies to all ionic components in the solution.
NRTL-SAC Local Composition Term
The segment-based excess Gibbs free energy of the local interactions for
systems with multiple molecular segments m and a single electrolyte segment
e (with a single cation segment c and anion segment a) can be written as
follows:
(12)
(13)
(14)